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What Does It Mean When You Find A Lump On Your Dog?

Any bumps can be scary, but here's how to know when it's serious.

You’re giving your dog his nightly belly rub, when suddenly you feel something that wasn’t there before. You try to stay calm as you investigate, pushing back his fur, but what exactly are you looking for?

Feeling the occasional lump or bump on a dog is fairly common — especially as our pets age — but that certainly doesn’t stop us from worrying about our canine friends.

Dogs develop protrusions under the skin for a variety of reasons, explains Dr. Betsy Golden, a veterinarian at DoveLewis Veterinary Emergency and Specialty Hospital in Portland, Oregon, and they can be difficult to diagnose without the help of a professional. Just like humans, these pesky bumps can range from an infected hair follicle, to a harmless fatty deposit, to something more serious.

How can you tell the difference? Here are a few tips about lumps and bumps every pet owner should know:  


“One of the most common ‘under the skin’ lumps is called a lipoma, or fatty tumor, which is typically not cancerous,” Golden tells The Dodo. “Lipomas tend to show up on middle-aged to older dogs of any breed, although large breed dogs and overweight dogs are more prone to them.”

To identify a lipoma, the lump will feel “soft and movable” under the skin, notes PetMD. Often dogs develop lipomas on their bellies, though these lumps can appear anywhere. Lipomas typically will not bother your dog or require treatment unless they impede his movement. If your dog gets one in a sensitive area, like under the front leg, it may have to be removed by a vet, Golden explains.

While lipomas are typically benign, it is recommended that any mass be examined by your vet.    

“Unless you’re sure about the cause of a lump or bump, bring your dog in for an exam,” Golden says. “Fast growth or sudden appearance, swelling, color change, pus or changes in your dog's behavior are all reasons to make a vet appointment right away.”

Warts, cysts and abscesses

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Being covered with fur has the pleasant effect of hiding dermatological issues — like (gasp) a pimple — but dogs can also suffer from uncomfortable infections under their skin.

“Other common non-cancerous lumps include warts, which will go away on their own or can be surgically removed, and sebaceous cysts, which are similar to large pimples,” Golden notes. “Abscesses can also cause what appear to be fast-growing and painful lumps, and are the result of an infection under the skin.”

These issues can happen to dogs of any age, and should be examined by a vet. “Vets can take a sample from the lump, either with a needle or by means of a surgical procedure, and determine the type of lump by looking at the cells under a microscope,” Golden explains. “Abscesses are opened and drained, and the dog is typically started on antibiotics and pain medication. Sebaceous cysts do not typically require treatment unless they become infected.”

Cancerous tumors

Cancer may be the leading cause of death in dogs over the age of 10, Dave Ruslander, a veterinary oncologist at Veterinary Specialty Hospital, told WebMD, but there are plenty of treatment options that can prolong your dog’s life. Cancerous growths can be either malignant or benign, and may spread quite rapidly if left untreated.

Symptoms can include a lump, swelling, lameness and unexplained bleeding. Your veterinarian will talk with you in more detail about any lumps that are diagnosed as cancerous, but for lumps such as skin tumors, mast cell tumors and breast cancer, surgical removal is often recommended. As with any lump or bump, the sooner you identify it and bring your pup to the vet, the better chances you will have treating it quickly.

To help find the cure for both people and pets, donate to the Animal Cancer Foundation